Thermostatic trap



Oct. 12, 1937. w T MIXSELL I 2,095,709

THERMOSTAT I C TRAP Filed July 20, 1936 Patented Oct. 12, 1937 UNITEDSTATES PATENT OFFICE 2,095,709 THERMQSTATIC TRAP Ward T. Mixsell,Washington, 0., Application JulyZll, 1936,Serial No. 91,597

5 Claims. (crass-5s) This invention is an improvement in devices knownas traps, whose function is to discharge air and water from steam-heatedsurfaces, and prevent the discharge of steam therefrom.

They are classed as float traps when a float mechanism is employed tocontrol the outflow of water and maintain a water seal to prevent theescape of steam, and as thermostatic traps when an expansible member isused, which dis- 1' tends when incontact with steam and closes a valve.These two elements are used in combination, the float to control thedischarge of Water and the thermostat to control the discharge of air.

This invention belongs to this latter class, and

is a device to reduce the combination of these elements to such a simpleform that it may be made sufiiciently small in size, and at a low cost,to be used on radiators, in lieu of the small and least efficientthermostatic traps, wherebythe positive action of a float to dischargewater and maintain a water seal against the discharge of steam isemployed, and a thermostatic element is so located that it is free fromthe temperature influence of the water, and can be designed to closeonly when in contact with steam at 212 F. is used, insuring completeventing of a radiator. This combination of a float and thermostat,permits the use of two ports, one suficiently large to pass the requiredamount of water, and one smaller port or orifice for air discharge, torestrict the venting, and prevent radiators nearest the boiler fromtaking steam too fast, causing the steam to flow to the ends of themains, up the several risers to all radiators uniformly.

One form of the invention is illustrated in the accompanying drawing inwhich:--

Fig. 1 is a central vertical section of the device. Fig. 2 is ahorizontal section on the line 2-2 of Fig. 1. a

This trap consists of a body I with inlet and outlet ports Ill and II, acap l2 screwed into same; a cylinder 2 attached either tothe body or thecap, open at the bottom for the admission of water, and having three(preferably) slotted openings l3, for the passage of air, steam, andwater; this cylinder, when water-sealed, forms an inner chamber, andalso protects the float from water hammer; a float 3 is located withinthe cylinder, with pads 5 concentrically arranged, to space same in thecylinder, so that it will be free from capillary attraction, and move ina straight line, an air tube 4 through the float, its lower end seatingagainst the seat B, around the discharge port, controlling the dischargeof water according to its height oif the seat, an air orifice A in aseat 8 at the topof this air tube of smaller diameter than the tube; anexpansible member or thermostat 6 located above the float and preferablyabove the inlet port in the body, comprising flexible discs, forming aflat cylinder, containing a volatile liquid, to which is attached avalve to close the air orifice; the float and thermostat being joined bya yoke l, forming a single movable unit.

The air tube 4 is preferably of hard phosphorbronze, silver soldered tothe float; the guides 5 of phosphor bronze, soldered to float to spacesame in the cylinder, so that it will be free from capillary"attraction, and move in a straight line;

the thermostat 6 of two manganese bronze corrugated flexible discs,containing a volatile fluid, with such a limited movement as to insureits remaining flexible indefinitely; the yoke l of manganese bronzesilver soldered to float and thermostat; the seats 8 of the air orificeand water outlet ports valve seats are of hard noncorrosive asbestoscomposition suitable for steam temperatures.

The operation is as follows: Assuming that the float valve is closedover the port B, air entering the body passes through the slot [3 in thecylinder and through the vent orifice A and tube 4 and out the port B.When condensation occurs (the float valve being still seated on B) itflows into the body and up into the cylinder until the water covers theslots l3 and closes air communication between the inside and outside ofthe cylinder. Then, as the inner chamber in the upper part of thecylinder is in communication with the outlet port B through the tube 4,the 'air will escape through the outlet port, reducing the air pressurein the upper part of the cylinder below that outside of the cylinder,which is that of the steam pressure existing in the radiator. Then thewater will rise higher in the cylinder than in the trap body, due tothis 'difierence of pressure, and cover the entire float, exerting a'maximum floatative efiect and lifting the float to open the port B forthe discharge of the condensation. When the float valve is closed on Bit will be apparent that the area exposed to air pressure on the bottomof the float is less than that of the top, by the area of the valve onB. But the floatative effect incident to the increased rise of water inthe cylinder resulting from the low pressure in the upper part of thecylinder (as above described) is sufficient to lift the floatnevertheless.

If dry steam is admitted to the trap, the ther- I from radiation throughthe cap, same will partially condense, lowering the pressure above thefloat, and as in the previous case, and the water will rise higher inthe cylinder thanin the trap body, and due to the added submergence ofthe float, and difference of pressure existing, will so equalize thedifference in areas, that the float will rise.

ing in air at a low temperature, when thesteam inflow and the rate ofcondensation'is excessive;

then the water will cover the slots preventing the flow of air throughthe trap, temporarily air binding the radiator, stopping the inflow ofsteam, causing same to flow along the other ra diators. V

This arrangement of float, slotted cylinder, and chambers with differentpressures permits the use of a small direct-acting float, (withoutlevers, valves, etc.) without flooding the radiator.

The most commoncomplaint of owners of heating plants is that, in mildweather we have to overheat some'rooms, in order to have otherroomssufliciently warm, I This condition should not obtain in anygravity vaporsystem. In hot water, single-pipe steam, and vacuum systemsit is unavoidable, but in a vapor system with proper piping, radiatorsupply valves, main vent valves, and the present traps on each radiatorit can be eliminated toe, high degree.

Thermostatic traps have large or ports which are fully open whensteaminitially flows into the radiators; there is no resistance to theoutflow of .and the radiators nearest the boiler, even with orifices inthe supply valves, take steam freely, and the disparity in steam supplymay vary as much as l%-150% between the first and last radiators in asystem.

The large port in the thermostatic valve is necessary for when theattached radiators are fully heated and condensation is at a maximum andsteam is at the trap, it is 9 or even 99% closed, and its area must thenbe sufficient to pass a maximum volume of condensate, 1

With the present trap, the float acting independent of the temperatureof the condensate or of steam at the trap, can pass a volume equal toits maximum capacity at the pressure then occurring, and as theair isdischarged through a separate port, thermostatically controlled,

. it is possible to reduce this port to a orifice or 4/ to the area .ofthe portof a thermostatic valve, and to so restrict the'venting of eachradiator as to attain a moreuniform distributionof steam-vaporthroughout'the. entire system, and an equal supply to each radiator. f

It is claimed that with steam and return mains running parallel,gradingin the same direction, the first radiator off the main being thefarthest from the main air vent, the steam main vented 'direct to theatmosphere through-a thermostatic valve with port for 2%;"Jand 3 sizesand a valve port for 3 and 4" sizea 1" valve with port for the 5" and 6"sizes, the return main vented through a float vent trap, Without a checkvalve and each radiator fitted with the present trap, steam will flowfrom the boiler to the ends of the mains in one-half or two-thirds thetime with the same intensity of fire. The designed pressure drop will bereduced 40% for 4 oz., 50% for 6 oz., and 60% for 8 .oz. in the entiresystem. The rise in pressure after the thermostatic vents at the end ofthe mains are closed will increase twice as fast:

, The disparity in distribution of steam to each j The slots l3 haveanother function, that of" controlling the venting of a cold radiator"standradiator first to the last will be reduced over 50 %1 to 75%. Thatthis restricted venting lowering the initial velocity of steam in therisers and runouts will eliminate clicking and gurgling particularlywith convector radiators which, having a small volume, take steam veryfast; That with gas, oil, or stoker-flred plants, the system willrespond more quickly and uniformly to the demands of the thermostat.That gravity vapor systems so installed will operate to provide a widerrange of heat control in the entire system, and in each separate room,than other systems. That by eliminating overheating, an economy in fuel,ranging from 5% to may be attained.

I claim:

1. A trap comprising a body having a discharge port at the bottomthereof, said body forming a high pressure chamber, a cylinder closed atthe top and open at the bottom, depending, in said body, said cylinderhaving an opening in its side wall, and forming a low pressure chamberin the upper part of the cylinder when the opening is closed by wateraccumulating in the body, a float in the cylinder, a tube extendingthrough the float and having an air port at the top and controlling saiddischarge port at the bottom of the body, and a thermostatic valvesupported on top of the float and controlling the air port.

2. A trap comprising a body having an upper inlet and a lower outletport, said body forming a high pressure chamber, a cylinder closed atthe top and open at the bottom and depending in the body, said cylinderhaving a slot in its side wall mostatic valve being above the level ofthe opening in the cylinderwall. 4. A trap as in claim 1, the lower endof said tube extendingbelow the float and surrounding the dischargeport.

5. A trap as in claim 2, the float of the float valve being mainly belowthe inlet port and the thermostat of the thermostatic valve being/abovesaid port. V I WARD T. MIXSELL.

